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How will you insert, delete and retrieve elements from a HashMap collection in Java?

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Pragya Keshap answered on February 4, 2023 Popularity 1/10 Helpfulness 1/10

answer How will you insert, delete and retrieve elements from a HashMap collection in Java?

How will you insert, delete and retrieve elements from a HashMap collection in Java?

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We use following methods to insert, delete and retrieve elements in

a HashMap.

1. Retrieve: We use get() method to retrieve elements from a

HashMap.

Value get(Object key)

2. Insert: We use put() method to insert a key value pair in a

HashMap.

Value put(Key k, Value v)

3. Delete: We use remove() method to delete key-value pair

from the HashMap.

Value remove(Object key)

class Book {    
int id;    
String name,author,publisher;    
int quantity;    
public Book(int id, String name, String author, String publisher, int quantity) {    
    this.id = id;    
    this.name = name;    
    this.author = author;    
    this.publisher = publisher;    
    this.quantity = quantity;    
}    
}    
public class MapExample {    
public static void main(String[] args) {    
    //Creating map of Books    
    Map<Integer,Book> map=new HashMap<Integer,Book>();    
    //Creating Books    
    Book b1=new Book(101,"Let us C","Yashwant Kanetkar","BPB",8);    
    Book b2=new Book(102,"Data Communications & Networking","Forouzan","Mc Graw Hill",4);    
    Book b3=new Book(103,"Operating System","Galvin","Wiley",6);    
    //Adding Books to map   
    map.put(1,b1);  
    map.put(2,b2);  
    map.put(3,b3);  
      
    //Traversing map  
    for(Map.Entry<Integer, Book> entry:map.entrySet()){    
        int key=entry.getKey();  
        Book b=entry.getValue();  
        System.out.println(key+" Details:");  
        System.out.println(b.id+" "+b.name+" "+b.author+" "+b.publisher+" "+b.quantity);   
    }    
}    
}

https://www.javatpoint.com/java-hashmap

Popularity 1/10 Helpfulness 1/10 Language java

Source: Grepper

Tags: elements hashmap java

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Contributed on Feb 04 2023

Pragya Keshap

0 Answers Avg Quality 2/10

How will you insert, delete and retrieve elements from a HashMap collection in Java?

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